Psycho-acoustic projector

ABSTRACT

BROADLY, THIS DISCLOSURE IS DIRECTED TO A SYSTEM FOR PRODUCING AURAL PSYCHOLOGICAL DISTRUBANCES AND PARTIAL DEAFNESS OF THE ENEMY DURING COMBAT SITUATIONS. ESSENTIALLY, A HIGH DIRECTIONAL BEAM IS RADIATED FROM A PLURALITY OF DISTINCT TRANSDUCERS AND IS MODULATED BY A NOISE, CODE OR SPEECH BEAT SIGNAL. THE INVENTION MAY UTILIZE VARIOUS FORMS AND MAY INCLUDE MOVABLE RADIATORS MOUNTED ON A VEHICLE ORIENTED TO CONVERGE AT A DESIRED POINT, INDEPENDENTLY POSITIONED VEHICLES WITH A COMMON FREQUENCY MODULATOR, OR MEANS EMPLOYED TO MODULATE THE ACOUSTICAL BEAM WITH RESPECT TO A FIXED FREQUENCY. DURING COMBAT, FRIENDLY FORCES WOULD BE EQUIPPED WITH A REFERENCE GENERATOR TO PROVIDE AURAL DEMODULATION OF THE PROJECTED SIGRAL, THEREBY YIELDING AN INTELLIGIBLE BEAT SIGNAL WHILE ENEMY PERSONNEL WOULD BE RENDERED PARTIALLY DEAF BY THE PROJECTED SIGNAL AS WELL AS BEING UNABLE TO PERCIEVE ANY INTELLIGENCE TRANSMITTED IN THE FORM OF A MODULATED BEAT SIGNAL.

Feb. 23, 1.9.71 4, E, FLANDERS 3,566,341

PSYCHO ACOUSTIC PROJECTOR Filed Aprii 27; las? O l `2 sheets-sheet 1` /msg I $.33 'gs l 'Sq SQ s NQ; (L

Has/wf Filed April 27'. 1967 A. E. FLANDERS PSYCHO-ACOUSTIC PROJECTOR 2 Sheets-Sheet 2 Has/vr United States Patent O1 hee 3,566,347 PSYCHO-ACOUSTIC PROJECTOR Andrew E. Flanders, Pomona, Calif., assignor to General Dynamics Corporation, a corporation of Delaware Filed Apr. 27, 1967, Ser. No. 634,348 Int. Cl. H04b 11/00 U.S. Cl. 340-- 7 Claims ABSTRACT OF THE DISCLOSURE Broadly, this disclosure is directed to a system for producing aural psychological disturbances and partial deafness of the enemy during combat situations. Essentially, a high directional beam is radiated from a plurality of distinct transducers and is modulated by a noise, code or speech beat signal. The invention may utilize various forms and may include movable radiators mounted on a vehicle and oriented to converge at a desired point, independently positioned vehicles with a common frequency modulator, or means employed to modulate the acoustical beam with respect to a fixed frequency. During combat, friendly forces would be equipped with a reference generator to provide aural demodulation of the projected signal, thereby yielding an intelligible beat signal while enemy personnel would be rendered partially deaf by the projected signal as well as being unable to perceive any intelligence transmitted in the form of a modulated beat signal.

BACKGROUND OF THE INVENTION This invention is directed to means for producing undesirable noise, and more particularly to a means for providing intense aural psychological disturbance and temporary partial deafness as an aid in personal type combat while additionally providing long distance voice communication.

Many prior devices have :been developed wherein physically damaging noises are employed to rid a given area of undesirable pests as exemplified by IU.S. Pats. 2,922,- 999; 3,058,103; and 3,113,304. Other prior efforts have been directed to providing ear lters which are employed to block damaging signals `while allowing desired signals to be heard as illustrated by U.S. Pat. 3,098,421, while other prior efforts have been directed to ambient noise reduction systems such as found in U.S. Pats. 3,057,960 and 3,133,990. However, no known prior effort has been directed to the modulation of an undesirable, unwanted or noise signal by a desired intelligible signal nor the use of such a system in a combat environment.

SUMMARY OF THE INVENTION The present invention advances the state of the art by providing a means for producing intense aural psychological disturbance and temporary partial deafness as an aid in personal type combat, while being utilized for voice communication by properly equipped friendly personnel.

Therefore, it is an object of this invention to provide a system capable of producing aural psychological disturbance while simultaneously providing voice communication.

A further object of the invention is to provide a means for radiating a highly directional beam from a plurality of distant transducers which is modulated by a noise, discretely coherent tone or beat, code or speech beat signal.

Another object of the invention is to provide intense aural psychological disturbance and temporary partial deafness as an aid in personal type combat.

Another object of the invention is to provide intense aural psychological disturbance to certain individuals Patented Feb. 23, 1971 while simultaneously providing effective communication with other individuals (while maintaining radio silence).

Other objects of the invention will become readily apparent from the following description and accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view illustrating an embodiment of a system for carrying out the invention;

FIG. 2 is a block diagram illustrating an embodiment of the circuitry which composes the FIG. 1 difference frequency modulator; and

FIG. 3 is a schematic illustration of an embodiment of the FIG. 2 paraphase inverter.

As illustrated in the drawings, a highly directional acoustic beam is provided by a plurality of moderately high frequency, high power radiators. Each one of the radiators may consist of an array of transducers operating on an acoustical carrier frequency in the vicinity, for example, of 5 or 6 kc. The carrier frequency region of operation is selected to provide a maximum of directivity with a minimum of attenuation with distance. One carrier frequency differs from the other iby the amount desired to convey the signal of interest. The resulting beat or combination frequencies supplied by virtue of ear non-linearity may be irritating noise, code or speech. Amplitude modulation may also be employed as desired.

Referring now to FIG. l, the illustrated embodiment comprises three (3) high power radiators or speaker units 10, 11 and 12 operating in the frequency range, for example, of 5 to 6 kc. and with a difference frequency of about c.p.s. Units 10, 11 and 12 are operatively connected to power amplifiers 13, 14 and 15, respectively, and positioned so as to direct acoustic beams 116, 17 and 18, respectively, to a single area indicated generally at 19 to provide a high intensity field 20| within which the person or victim indicated at 21 is located. -Each of the power amplifiers 13, 14 and 15 are electrically connected to a difference-frequency modulator 22, while the input to pre-amplifier 29 is connected via a switch generally indicated at 31 to either of a pair of transducers, such as a microphone 32 or a tape recorder unit 33. An amplitude modulator 34 is positioned such that it is adapted to be connected intermediate the diiference-frequency modulator 22 and the power amplifiers 14 and 15, and to the pre-amplifier 29. The output of the amplitude modulator 34 indicated at 35 is operatively connected to switch 24. Switch -30 is constructed such that the blade 36 thereof is movable to interconnect a terminal 37 connected to difference-frequency modulator 22 and a terminal 38 connected to the amplitude modulator 34, such that the output of pre-amplifier 29 may be operatively connected to both modulators 22 and 34. The amplitude modulator 34 may also be connected to the output signal 215 of dilference-frequency modulator 22 via a switch generally indicated at 39 which includes a blade element 40 movable between a terminal 41 connected to switch 24 and a terminal `42 connected to the input of modulator 34. Switch 31 includes a blade `43 which is movable between a terminal 44 connected to microphone 32 and a terminal 45 connected to tape recorder 33.

While not shown, it is within the scope of this invention to gang the switches 30 and 39 such that the output signal 25 from the diiference-frequency modulator 22 and the output from the pre-amplier 29 may be simultaneously directed into the amplitude modulator 34. Also, switch 24 may be modified such that the output from either the amplitude modulator 34 and/or the output signal 25 from the difference-frequency modulator 22 may be directed simultaneously to radiators 14 and 15. While the switches have been illustrated and described as blade type switches for simplicity of explanation, these switches may also be of push-button, micro-switch or any of the other various electronic switches adaptable for the specific circuits in which they are utilized.

An embodiment of the difference-frequency modulator 22 is illustrated by block diagram in FIG. 2. The output signal from the pre-amplifier 29 is directed via terminal 27 to an amplifier 46 which increases the strength of the signal as known in the art. The amplifier 46 may be any amplification-producing device capable of increasing the strength of the signal by transferring power to the signal from an external source without appreciably altering its characteristic waveform. The output from amplifier 46 is fed into a limiter 47, which as known in the art, is a circuit that limits the amplitude of its output signal to some predetermined threshold level. The signal from limiter 47 is fed into an audio filter 48 which, as known in the art, functions to transmit a desired range of energy while substantially attenuating all other ranges. The output from filter `48 is then fed through an AC integrator 49 which, in this instance, may be an RC circuit with the capacitor to ground, which supplies a signal inversely proportional to frequency into a paraphase inverter 50. 'Ihe paraphase inverter 50 described in detail hereinbelow with respect to FIG. 3, may, for example, be a transistor with equal emitter and collector resistors wherein the gain is 1 and in which the two output signals indicated at 51 and 52 differ in phase by 180. As seen in FIG. 2, the signal 51 is positive while the signal 52 is negative. The paraphase inverter output signals 51 and 52 are fed, respectively, into diodes 53 and 54 wherein the signals are rectified, as known in the art, and the output from the diodes 53 and 54 are combined in a full-wave RC filter circuit indicated at 55 and the combined signal is fed into an emitter follower 56. The RC lter circuit 55 may comprise, for example, a resistance to ground in parallel with a bypass capacitor. The emitter follower 56 is a grounded-collector transistor amplifier which functions as known in the art. The output signal from the emitter follower 56 is fed through an amplifier 57 into a paraphase inverter 58 Which may, for example, be identical to the previously described paraphase inverter 50 and illustrated in FIG. 3. As in the inverter 50, the output signals from the paraphase inverter 58 indicated at 59 and 60, differ in phase by 180 with the signal 59 being positive while the signal i60 is negative. The output signals 59 and 60 are fed, respectively, into voltage-controlled oscillators -61 and 62. As known in the art, the frequency of oscillation of each of the oscillators 61 and 62 can be varied by changing the applied voltage. By way of example, oscillators 61 and 62 are set such that their output signals 23 and 25, respectively, have a difference of 100 cycles per second (c.p.s.), and are utilized as described above with respect to FIG. 1.

Referring now to FIG. 3, an embodiment of the paraphase inverter 22 of FIG. 2 is illustrated, the FIG. 3 embodiment also being illustrative of the paraphase inverter 58 of FIG. 2. The output signal from the AC integrator 49 is fed to the base 63 of a transistor generally indicated at 64. The collector y65 of the transistor A64 is conductively connected through a load resistor R1, to a positive source, while the emitter 66 is conductively connected through a load resistor R2 to a negative source. Resistors R3 and R4 function as bias resistors for the transistor 64 as known in the art. The output 51 is taken intermediate collector l65 and resistor R1 while output 52 is taken intermediate emitter 66 and resistor R2. Each of the output signals 51 and 52 are fed through an RC coupling network composed of blocking capacitors 67 and 67' and resistors 68 and 68 connected to ground. As indicated in FIG. 3, the output signals 51 and 52 are then fed into similarly polarized diodes 53 and 54, respectively, as described above with respect to FIG. 2.

While not shown, appropriate power sources are utilized for the various circuits and components as required.

The invention may be utilized in many different applications. One application may use t'wo movable radiators or speaker units mounted on a single vehicle or aircraft and which are directed so as to converge at the appropriate range. Another application may use two independently positioned vehicles, aircraft, tripods, or combination thereof with a common difference frequency modulator. Another application used for communication purposes would modulate the acoustical beam with respect to a fixed frequency, wherein a small audio generator (not shown) carried by the listener (receiver) would mix aurally via the ear with the projected modulated carrier to provide intelligible messages, the carrier by itself being unintelligible by virtue of high frequency transposition.

As an aid to pointing compensation for beam deflection caused by atmospheric temperature gradients, it is within the scope of this invention to deploy down range microphones or microphone-transmitter combinations.

Friendly personnel in the vicinity of the sound field 20 can use narrow band audio filter ear muffs or plugs, as known in the art, so as to maintain reasonable hearing threshold sensitivity. On the other hand, enemy personnel not similarly equipped for the transmitted pass band would lose about 40 db in hearing sensitivity similar to partial deafness. This would place the enemy at a distinct aural acuity disadvantage during close-in operations.

For speech transmission, the elemental vowel formant frequencies are provided by the carrier difference ,f1-f2. The carriers 23 and 25 may be frequency modulated differentially or one remained fixed. The consonant sounds are contained in the amplitude modulation of one or both carriers as described `with respect to FIG. 1. The listener needs no fixed frequency sound source in this mode of operation.

It has thus been shown that this invention provides intense aural psychological disturbance and partial deafness as an aid in personal type combat, while being adapted to simultaneously provide voice communication.

While a particular embodiment of the invention has been illustrated and described, modifications and changes will become apparent to those skilled in the art, and it is intended to cover in the appended claims all such modifications and changes as come within the true spirit and scope of the invention.

What I claim is:

.1. A system for producing an intelligible signal, aural psychological disturbances and partial deafness cornprlsmg:

(a) a plurality of radiator means capable of transmitting a highly directional acoustic beam;

(b) a difference-frequency modulator means for generating a pair of carrier signals, each of said carrier signals being of a different frequency;

(c) a separate power amplifier means for amplifying each of said carrier signals, each of said power amplifier means operably connected to said differencefrequency modulator means, each of said plurality of radiator means operably connected with an output from an associated one of said power amplifier means;

(d) each of said plurality of radiator means being positioned so that the acoustic beam transmitted therefrom converges in a common area to produce a high intensity field;

(e) an amplitude modulator operably connected to an input of an associated one of said power amplifier means;

(f) means operatively connected to said differencefrequency modulator means for selectively feeding one of said carrier signals through said amplitude modulator;

(g) audio signal generating means operably connected to said difference-frequency modulator means for feeding an audio signal into said difference-frequency modulator means; and

(h) selective means operatively connected to said amplitude modulator for additionally feeding and audio signal into said amplitude modulator;

whereby the resulting combination of frequencies in the common area of convergence produce both an irritating noise and an intelligible signal within said high intensity field.

2. The system defined in claim 1, wherein said audio signal generating means includes a pre-amplifier operably connected to said difference-frequency modulator means; at least one audio signal transducer; a switch means operatively connected to said at least one audio signal transducer and to said pre-amplifier for feeding an audio signal to said pre-amplifier, the output of said pre-amplifier being fed to said difference-frequency modulator means.

3. The system defined in claim 2, wherein said audio signal transducer is a microphone.

4. The system defined in claim 2, wherein said audio signal transducer is a tape recorder unit.

5. The system defined in claim 1, wherein said plurality of radiator means includes at least three radiator means, each of said three radiator means being fed from an associated power amplifier means, one of said power amplifier means being operatively connected with said difference-frequency modulator means such that one of said carrier signals therefrom is fed to said one power amplifier means, and wherein a switch means is operatively connected to the other two of said power amplifier means and to said difference-frequency modulator means such that the other of said pair of carrier signals therefrom is selectively directed to said other two power amplifier means.

6. The system defined in claim 1, wherein said difference-frequency modulator means comprises: an amplifier means operatively connected to receive the audio signal from said audio signal feeding means, a limiter fed by the output from said amplifier means, an audio filter means operatively connected to receive the output signal from said limiter and feeding the output thereof to an AC integrator, a paraphase inverter operably connected with said AC integrator and fed by the output signal therefrom, said paraphase inverter functioning to produce a pair of output signals which are fed into a pair of diodes, the output from said diodes being combined in an RC filter circuit and fed to an emitter follower, a second amplifier means operatively connected to said emitter follower so as to receive an output signal therefrom, a second paraphase inverter being fed by the output from said amplifier means and functioning to produce a pair of output signals which are fed into a pair of voltage controlled oscillators, the output thereof constituting said carrier signals.

7. The system defined in claim 6, wherein said paraphase inverters each include a transistor unit having a base, an emitter and a collector, the input to the transistor unit being fed into the base, said collector being connected through a first load resistor means to a positive voltage source, said emitter being connected through a second load resistor means to a negative voltage source, a pair of bias resistor means operatively connected to said base, one of said bias resistor means being also operatively connected intermediate said first load resistor means and said positive voltage source, the other of said bias resistor means being also operatively connected intermediate said second load resistor means and said positive voltage source, a first RC coupling network operatively connected intermediate said collector and said first load resistor means, a second RC coupling network operatively connected intermediate said emitter and said second load resistor means, the output signals from said RC coupling networks constituting said pair of output signals.

References Cited UNITED STATES PATENTS 2,922,999 1/1960 Carlin 34-015 RODNEY D. BENNETT, Primary .Examiner I. G. BAXTER, Assistant Examiner U.S. C1. X.R.. 340--3 84 

